The purpose of the proposed research is to determine the effect of somatosensory deafferentation of fetal primates on their postnatal behavioral development. Through the use of recently developed intrauterine surgical techniques, immature fetuses will be exposed at different gestational epochs, subjected to dorsal rhizotomy, and then replaced in the uterus for the completion of embryonic development. Following delivery, the prenatally deafferented infants will be subjected to extensive behavioral devaluation, and their development will be compared with that of normal monkeys, monkeys deafferented in adolescence, monkeys deafferented on the day of birth, and sham-operated controls. Previous deafferentation experiments by the present investigators have been addressed to the task of determining whether somatic sensation, and sensory feedback in general, are necessary for various types of learning and for the performance of different categories of movement. We have found that monkeys that have undergone serial section of the dorsal roots innervating the forelimbs are capable of extensive purposive movement. However, all subjects that have previously been successfully studied were deafferented after birth. It therefore remains possible that somatosensory feedback and spinal reflexes are necessary in prenatal life for the later development of various classes of behavior. The results from this research should provide information concerning the degree to which basic motor programs for different patterns of behavior are present in the primate CNS before birth. The project should also provide data on the nature and extent of plasticity within the fetal nervous system at different gestational ages.